Apparatus for the annealing of metal



June 13, 1939. w VREELAND 2,162,143

APPARATUS FOR THE ANNEALING OF METAL Filed July l, 1937 2 Sheets-Sheet 2V\ m Y &9 a

C N L "D Gear' call rflaroa NJ) I Patented June 13, 1939 PATENT OFFICEAPPARATUS FOR THE ANNEALING OF METAL George W. Vreeland, Maplewood, N.J., assignor to H. A. Brassert & Company, Chicago, Ill., a corporationoi' [Ilinois Application July 1, 1937, Serial No. 151375 1 Claim.

This invention relates to a new and-improved apparatus for the annealingof metal and to such a method particularly adapted for the annealing ofsteel strip or w'ire in coils.

The proper annealing of metal requires its gradual heating to apredetermined temperature, its maintenance at that temperature for agiven time, and its proper cooling. The tempe'aturcs, temperaturegradients and times will vary with difierent metals and diiferingconditions and requirements.

In general, annealing at present is carried out by three difierentmethods. The usual box method is one in which an ordinary type ofregenerative or recuperative iurnace which is rectangular in plan, isused and coils are placed in the boxes in a row or rows within thefurnace chamber, the fuel burning on the outside of the boxes. This isinefiicient to fuel consumption and in uni- 20 formity of heating, andalso requires additional apparatus tor removing and installing the boxesin the furnace.

Another method is that of the removable cover annealing furnace, wherethe material is placed 2 in the furnace without individual covers, andthe heating is carried on in tubes placed variously in the furnace. Thetubes are heated by burning gas in them or passing highly heated gasthrough them.

The third method is the electric furnace method where heating coils areprovided around the walls of the furnace and in some cases in the centerof the Iurnace. This method involves an excessively high cost ofinstallation and high electric fuel cost, especially in comparison withplants that have available their own gaseous fuels. such as blat furnacegas, coke oven gas or a mixture of these gases.

It is an object of the present inventicn to pro- 40 vide new andimproved apparatus for annealing. It is a further object to provide afurnace which is low in cost of manufacture and of maintenance.

It is also an object to provide a furnace for 45 using eificiently lowgrade and inexpensive fuel such as blast furnace gas. l

It is an additional object to provide an apparatus which aflords rapidand uniform heating all around the coils of metal being treated and bywhich, during the cooling stage, the covers for the metal are exposed tothe air to accelerate cooling.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of a furnace of my invention,in the accompany- ?ne drawings, in which- Figura 1 is a partly brokenaway plan view of a furnace, with the wall in section;

Figure 2 is a fragmentary vertical section of the furnace of Figure 1;and

Figure 3 is a view of a portion of Figure 2 but showing a modified formof construction.

Referring first to Figures 1 and 2, there is provided a circular base llhaving a metal outer wall !2. This base provides a circular trench !3which provides a combustion space for a plurality of low pressureburners ll which enter tangentially from the periphery of the base.Gaseous fuel and air are provided for the burners M through pipes |5 andI 6. It will be understood that liquid fuel may be used if desired.

At the upper edge of the base a scaling trench l'l is provided which isfilled with sand for sealing purposes. located in the center of the baseand the waste gas oiftake passa ze !9 is locatedsubstantially in thecenter of the floor IS. The passage 19 is provided with a removablecover 20 which may be used when the chamber is not receiving heatinggases.

The coils of material being treated 2|, are placed on cast steel bases22 which are supported above the floor I& by blocks 23. The edge of thesteel base 22 carries a recess 24 receiving sand to seal the removablemetal box 25 which covers the coils 2l to be annealed. A thermocouple 26extends through the base 22 and is provided with an outside connection21 so that the temperature of the material being annealed may beconstantly observed. A tube 28 enters the box 25 through the base 22 forthe introduction of a non-oxidizing gas with which the box is filledduring the process. so as to force out air and prevent oxidation of thematerial being annealed.

The removable cover 2! fits onto the base I I and is provided with ametal flange 30 extending down into the sand seal recess I'I. This coveris provided with a lining of refractory material 3! and refractory roof32. It will be noted that the inner wall of the refractory lining 3| ofthe cover inclines inwardly and upwardly so as to direct the hot gasesfrom the trench |3 against and between the boxes 25.

In the form of construction shown in Figura 3, boxes 40 are providedwhich have central vertical flues 4l. These flues communicate withangularly inclined flues 42 in the base 13, these flues 42 extending tothe central flue 44 which is similar to flue i! of the form ofconstruction of Figures 1 and 2. The partia] cover 45 is pro- Thematerial receiving floor IB is vided for the opening of flue 44, whichcover serves to reduce the eflective area o! the flue and force some ofthe products o! combustion to pass down through flues "and into flue 44through flue 42. The thermocouple 45 and pipe 48 for introdcingnon-oxidizing gases, are also provided in this construction in the samemanner as that of Figures 1 and 2.

In general, an installation will preferably include three platforms anda single cover. Thus one platform may be used to put in place thematerial to be annealed, while a second platform is enclosed by thecover and is being used to heat material, and the third supportsmaterial in the process of cooling. The burners l4 are y put inoperation after the cover 29 is installed and the material is graduallybrought up to"'the desired temperature, the temperatures being ob servedby means of the pyrometers connected to the thermocouples 26.

In a preferred method of operation of the !urnace, where dead, softsteel is desired, a temperature of approximately 1500 F. is 'maintainedin the main body of the furnace and a temperature of within five degreesFahrenheit of 1350 F. is preferably reached within the coils !I in theboxes 25. It will be understand that during this heating operation,non-oxidizing gas is provided through pipes 28 so as to preventoxidation of the material being annealed.

The usual cycle consists in heating up for approximately fitteen hoursand then reducing the gas flow and equalizing the temperaturesthroughout the coils of material so as to present over or under heatingof the steel. The steel may be maintained at the predeterminedtemperature for approximately three hours and then be permitted to cool.The cover 29 is removed during the cooling, although the boxes 25 or 40are preferably not removed until the material has been reduced to atemperature of less than 250" F., after which oxidation is not ofimportance. It is preferable to install the covers 20 in aman-s thecentral passages IQ after the main !urnace cover is removed so as toavoid affecting the draft to the furnace being heated. Usually the threepassages i! in the three 'pases of an installaticn are connected to asingle stack and in addition, damper controls of the passages may i beprovided.

Under usual Operating conditions it is ordinarily prei'erable tomaintain a slight positive pressure throughout the chamber. If desired,waste heat may be used to preheat the air sent to the burners l4 forcombustion. If blast furnace gas alone is used, it may also be desirableto preheat it to increase the efliciency of operation.

In the form of construction shown in Figure 3,

the partia] cover 45' is installed during the heating-operation so as to'limit the passage of gases directly to the main central flue 44 andinsure that the desired portion of these will go down the central fiues4| of the boxes 40. The blocks 23 which raise the steel bottoms abovethe floor ll are desirable to insure uniform heating oi' the lower coilsand prevent cold bottoms which occur when the bases are placed directlyon the floor.

While I have shown certain preferred forms of apparatus for carrying outmy invention it is to be understood that the apparatus may be modifledto meet varying conditions and requirements and I contemplate suchchanges as come within the spirit and scope of the appended claim.

I claim:

A platform type annealing i'urnace, comprislng a platform ofsubstantially circular shape having burners extending inwardly at itsperiphery, waste gas withdrawing means adiacent the center, anintermediate, circularly extending material receiving floor. cylindricalmaterial receiving containers on said floor, said containers havingcentral vertical fiues, connections below said. fiues to the centralwaste gas withdrawing means, and a removable cover seating on saidplatform.

GEORGE W. VREELAND.

CERTIFICATE OF CORRECTION Patent No. 2,162,lh5.

June 1939.,

GEORGE w. VREELAND.

It ie hereby certifed that error appears in the printed specification ofthe above numbered patent requiring correction as followe: Page l, firstcolumn, line 19, for the word "to" read in; page 2, first column, line51 for "present" read prevent; and that the said Letters Patent shouldberead with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1959.

(Seal) Henry Van Arsdae,

Acting Commissioner of Patents.

vided for the opening of flue 44, which cover serves to reduce theeflective area o! the flue and force some of the products o! combustionto pass down through flues "and into flue 44 through flue 42. Thethermocouple 45 and pipe 48 for introdcing non-oxidizing gases, are alsoprovided in this construction in the same manner as that of Figures 1and 2.

In general, an installation will preferably include three platforms anda single cover. Thus one platform may be used to put in place thematerial to be annealed, while a second platform is enclosed by thecover and is being used to heat material, and the third supportsmaterial in the process of cooling. The burners l4 are y put inoperation after the cover 29 is installed and the material is graduallybrought up to"'the desired temperature, the temperatures being ob servedby means of the pyrometers connected to the thermocouples 26.

In a preferred method of operation of the !urnace, where dead, softsteel is desired, a temperature of approximately 1500 F. is 'maintainedin the main body of the furnace and a temperature of within five degreesFahrenheit of 1350 F. is preferably reached within the coils !I in theboxes 25. It will be understand that during this heating operation,non-oxidizing gas is provided through pipes 28 so as to preventoxidation of the material being annealed.

The usual cycle consists in heating up for approximately fitteen hoursand then reducing the gas flow and equalizing the temperaturesthroughout the coils of material so as to present over or under heatingof the steel. The steel may be maintained at the predeterminedtemperature for approximately three hours and then be permitted to cool.The cover 29 is removed during the cooling, although the boxes 25 or 40are preferably not removed until the material has been reduced to atemperature of less than 250" F., after which oxidation is not ofimportance. It is preferable to install the covers 20 in aman-s thecentral passages IQ after the main !urnace cover is removed so as toavoid affecting the draft to the furnace being heated. Usually the threepassages i! in the three 'pases of an installaticn are connected to asingle stack and in addition, damper controls of the passages may i beprovided.

Under usual Operating conditions it is ordinarily prei'erable tomaintain a slight positive pressure throughout the chamber. If desired,waste heat may be used to preheat the air sent to the burners l4 forcombustion. If blast furnace gas alone is used, it may also be desirableto preheat it to increase the efliciency of operation.

In the form of construction shown in Figure 3,

the partia] cover 45' is installed during the heating-operation so as to'limit the passage of gases directly to the main central flue 44 andinsure that the desired portion of these will go down the central fiues4| of the boxes 40. The blocks 23 which raise the steel bottoms abovethe floor ll are desirable to insure uniform heating oi' the lower coilsand prevent cold bottoms which occur when the bases are placed directlyon the floor.

While I have shown certain preferred forms of apparatus for carrying outmy invention it is to be understood that the apparatus may be modifledto meet varying conditions and requirements and I contemplate suchchanges as come within the spirit and scope of the appended claim.

I claim:

A platform type annealing i'urnace, comprislng a platform ofsubstantially circular shape having burners extending inwardly at itsperiphery, waste gas withdrawing means adiacent the center, anintermediate, circularly extending material receiving floor. cylindricalmaterial receiving containers on said floor, said containers havingcentral vertical fiues, connections below said. fiues to the centralwaste gas withdrawing means, and a removable cover seating on saidplatform.

GEORGE W. VREELAND.

CERTIFICATE OF CORRECTION Patent No. 2,162,lh5.

June 1939.,

GEORGE w. VREELAND.

It ie hereby certifed that error appears in the printed specification ofthe above numbered patent requiring correction as followe: Page l, firstcolumn, line 19, for the word "to" read in; page 2, first column, line51 for "present" read prevent; and that the said Letters Patent shouldberead with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1959.

(Seal) Henry Van Arsdae,

Acting Commissioner of Patents.

